The present invention relates to a solenoid valve for which opening and closing of a flow path is controlled by applying current to a coil. The present invention is preferably applied, for example, to a brake fluid pressure control valve disposed in a conduit of an ABS actuator provided in a vehicular braking apparatus.
FIG. 10 is across sectional view of a conventional solenoid valve J1. In the solenoid valve J1, when current is not applied to a coil J2, a plunger J4 is urged by elastic force of a spring J3, and a ball J6 provided at a tip of a shaft J5 that moves together with the plunger J4 separates from a valve seat J8 of a seat valve J7. Thus, a conduit A is in an opened state. When current is applied to the coil J2, the plunger J4 is urged in resistance to the elastic force of the spring J3, and the ball J6 provided at the tip of the shaft J5 is seated on the valve seat J8 of the seat valve J7. Accordingly, the conduit A is in a closed state. Further, a vertical groove J9 that is parallel with a sliding direction of the plunger J4 is formed on the outer periphery of the plunger J4. Movement of fluid through the vertical groove J9 facilitates sliding of the plunger J4.
In the type of solenoid valve J1, when the conduit A is opened and closed quickly, fluid pulsation becomes more substantial and thus problems such as an abnormal noise occur. Accordingly, a groove portion J10 is provided on an outer periphery of the plunger J4, and a ring shaped member J11 made of a resin is disposed in the groove portion J10. An orifice (fluid throttle) J12 that communicates with the vertical groove J9 is provided in the groove portion J10, and thus, a sliding speed of the plunger J4 becomes slower and a fluid pulsation reduction effect is obtained.
In the above mentioned configuration, since the ring shaped member J11 is assembled arbitrarily, there are cases in which relative displacement of the orifice J12 and the vertical groove J9 is generated, making it difficult to ensure a flow path. Therefore, in order to ensure the flow path, a chamfered portion J13 is provided such that a side wall face of the groove portion J10 is tapered, and the fluid is allowed to pass through the chamfered portion J13.
In the aforementioned conventional solenoid valve J1, relative displacement of the orifice J12 and the vertical groove J9 is generated by arbitrary assembly of the ring shaped member J11. The relative displacement, as shown in FIGS. 11A and 11B, changes the flow path (as shown by arrows in the drawing) of the fluid that passes the orifice J12 and the vertical groove J9, causing variation in flow path resistance. In such a case, variation in the sliding speed, or the like, of the plunger J4 occurs, and thus it is no longer possible to obtain sufficient fluid pulsation reduction effect.
Moreover, if the flow path is ensured by providing the chamfered portion J13 on the groove portion J10, a cross sectional area D of a portion of the plunger J4 at which the chamfered portion J13 is provided becomes smaller. Accordingly, attraction force is reduced.
Further, assembly of the ring shaped member J11 to the plunger J4 is executed by press-expanding the ring shaped member J11 using a bias cut portion (a cut-through portion), not shown, which is formed in the ring shaped member J11. However, fluid leaks through the bias cut portion, and thus the sliding speed of the plunger J4. deviates from a required set value.
It is therefore an object of the present invention to provide a solenoid valve that is capable of obviating the above problems.
It is an object of the present invention to eliminate variation in the flow path resistance caused by arbitrary assembly of a ring shaped member having an orifice, and to ensure sufficient fluid pulsation reduction effect.
It is further object of the present invention to ensure a cross sectional area of a plunger to prevent decrease in attraction force.
Moreover, it is object of the present invention to prevent fluid leakage through a bias cut portion.
According to the present invention, a solenoid valve includes a vertical groove formed along a sliding direction of a plunger, a groove portion that is formed around an outer periphery of the plunger are provided on an outer peripheral surface of the plunger, a cylindrical member provided with a communication path having an orifice that allows fluid to move in a sliding direction of the plunger is fitted into the groove portion, a positioning portion restricting movement of the cylindrical member in a peripheral direction of the plunger is provided in at least one of the plunger and the cylindrical member, and the cylindrical member is assembled to the plunger such that the positioning portion aligns the vertical groove with the communication path having the orifice.
Accordingly, the positioning portion is able to align the vertical groove with the communication path formed by the orifice. Therefore, it is possible to prevent change of flow path that passes the orifice and the vertical groove of the plunger, and variation in a sliding speed of the plunger. As a result, it is possible to obtain sufficient fluid pulsation reduction effect.
A solenoid valve according to the present invention may be provided with, for example, a protruding portion that protrudes in an axial direction of the cylindrical member at a portion of the cylindrical member where the orifice is formed. This protruding portion serves as the positioning portion. By fitting the protruding portion into the vertical groove, it is possible to align the vertical groove with the communication path having the orifice.
Alternatively, a solenoid valve according to the present invention may be provided with a protruding portion that protrudes in a radial direction of the cylindrical member at an inner peripheral surface of the cylindrical member. The protruding portion serves as the positioning portion. A concave portion into which the protruding portion is fitted is provided in the groove portion. By fitting the protruding portion into the concave portion, it is possible to align the vertical groove and the communication path having the orifice.
A solenoid valve according to the present invention may be characterized in that a bias cut portion formed by a cut-through portion that divides the cylindrical member is formed in the cylindrical member. This bias cut portion is formed in a shape that inclines toward with respect to the axial direction of the cylindrical member. Such a construction allows the bias cut portion to be lengthened, and thus a flow resistance of the fluid becomes larger at the bias cut portion. Therefore, it is possible to inhibit fluid leakage through the bias cut portion.
A solenoid valve according to the present invention may be characterized in that a bias cut portion formed by a cut-through portion that divides the cylindrical member is formed in the cylindrical member. The bias cut portion is formed in a stepped shape having a portion that is parallel with a peripheral direction of the cylindrical member. In such a construction, even if the cylindrical member expands in the radial direction, the portion parallel with the peripheral direction of the cylindrical member of the bias cut portion shuts off the flow path at the bias cut portion. Accordingly, it is possible to prevent fluid leakage through the bias cut portion.
A solenoid valve according to the present invention may be characterized in that a side wall face of the groove portion of the plunger is not chamfered. In this case, however, some cases where chamfering of approx. 0.1 to 0.2 mm is allowed to remove burrs, or the like. Accordingly, it is possible to ensure a large cross sectional area of the plunger and prevent decrease in attraction force.
A solenoid valve according to the present invention may be characterized in that the orifice and a portion having a larger flow path area than the orifice are disposed in series along a flow direction of the fluid in the communication path having the orifice.
Accordingly, the orifice is shorter and dimensional accuracy in processing is improved, thereby reducing variation in the flow path resistance.
It should be noted that the above reference numerals in parentheses indicate individual portions. These reference numerals correspond with specific portions to be described in the later embodiments.